In the specification of French Patent No. 1,449,615 of Jan. 12, 1965, there is described such a staple draft device which includes two levelling-down or compacting rollers one of which co-operates with both the needled-surface feed control rollers; while the other co-operates solely with the feed roller at a location situated a little more upstream in relation to the direction of forward movement of the staple while being drawn off.
Now, such devices have disadvantages. Indeed, it has been established that on account of the relatively great thickness or depth of the staple laps which are nowadays worked on this type of machine, the needled-surface feed roller meets with difficulties in controlling the staple mass as the latter passes with some difficulty between the fallers of this roller, so that the upper stratum of staple is no longer controlled by the needles and is drawn-off irregularly or else not at all. If an attempt is made to force the staple lap completely down between the needles of the roller, it is found that the lower layers of staple are jammed between the bottoms of the needles and that drawing off of the fibres of the staple relative to one another no longer takes place. In order that the drawing-off might be carried out in a normal manner, it is necessary that the staple to be drawn be controlled in a set of needles in such manner that the fibres are able to slip relative to one another.